1. Field of Invention
This invention relates to a rotary mimeographic printing machine.
2. Description of Prior Art
Two kinds of rotary mimeographic printing machines are known in the art: In one of the rotary mimeographic printing machines, as disclosed for instance by Unexamined Japanese Patent Publication No. Hei. 3-24989, ink is supplied into the rotary cylindrical drum, and the press roller is operated to push a printing sheet against a stencil paper wound on the rotary cylindrical drum.
In the other rotary mimeographic printing machine, as disclosed by Unexamined Japanese Patent Publication No. Hei. 3-254984, the rotary cylindrical drum is made of flexible material, and an inside pusher roller is set inside the rotary cylindrical drum to elastically deform the tubular wall of the rotary cylindrical drum outwardly, and a lower pusher roller is provided outside the rotary cylindrical drum in such a manner that its rotary axis is in parallel with the axis of the drum. A printing sheet is set between the rotary cylindrical drum and the lower pusher roller, and then printed while being held between the lower pusher roller and the outer cylindrical wall of the cylindrical drum which is deformed by the inside pusher roller.
In order to adjust the top and bottom printing positions of the printing sheet, the above-described mimeographic printing machine has a sheet supplying mechanism for taking out printing sheets one at a time, and a pair of upper and lower sheet supplying rollers adapted to clamp and convey a printing sheet. Those upper and lower sheet supplying rollers are operated in synchronization with the rotation of the rotary cylindrical drum; that is, they are moved towards each other to clamp the printing sheet and convey it towards the rotary cylindrical drum (the printing station), and they are moved away from each other after the rotary cylindrical drum turns through a predetermined angle (or after it turns for a predetermined period of time).
When, in the above-described mimeographic printing machine, a printing sheet is not correctly conveyed along the sheet conveying path; that is, it is caught in the sheet conveying path, the machine is stopped to check abnormal points and to remove the sheet. In this case, sometimes the pair of sheet supplying rollers holding the printing sheet are stopped while being kept in contact with each other, and it is considerably difficult to remove the sheet from the sheet supplying rollers thus stopped. Furthermore, after being caught, the printing sheet may be pushed deep into the machine by the sheet supplying rollers. As is apparent from the above description, the conventional mimeographic printing machine suffers from the problem that, when a printing sheet is caught in the machine, it is considerably difficult to remove the printing sheet from the machine.